os.system("qemu-img create -f qcow2 -b \"%s\" \"%s\"" %
                  (newnames[i], i))
        os.chmod(i, 0o664)
    return 0

def cmd_snapshots(options):
    """ vws snapshots - list existing snapshots """
    if not options.stopped:
        print("Cannot list snapshots of running VW", file=sys.stderr)
        sys.exit(1)
    os.chdir(options.dir)
    drives = get_drives(options.dir)
    lst = []
    info = {}
    with os.popen("qemu-img info --backing-chain " + drives[0], "r") as f:
    with os.popen("qemu-img info -U --backing-chain " + drives[0], "r") as f:
        for line in f:
            if line.find(": ") != -1:
                var, val = line.strip().split(": ")
                if val != "":
                    info[var] = val
            elif line[0] == '\n':
                lst.append(info)

def cmd_commit(options):
    """
    Commits last snapshot changes into it's backing file
    There would be one snapshot less for virtual machine
    """
    if options.stopped:
        #
        # Stoppend vm - last snapshot is commited into its backing file.
        # Stopped vm - last snapshot is commited into its backing file.
        # Backing file is made current drive image
        #
        os.chdir(options.dir)
        found = 0
        for drive in get_drives(options.dir):
            backing = get_backing(drive)
            if backing is None:

    # Parse argument
    args = ArgumentParser(description="Manage Virtual Workstations")
    cmds = args.add_subparsers(dest='command', help="sub-command help")
    p = cmds.add_parser("list", help="List existing VWs",
                        description="List existing VWs")
    p.add_argument("-l", "--state", const=True, default=False, dest='state',
                   action='store_const', help='Show state of the machine')
    p.add_argument("--usb", action='store_const', const=True, default=False,
                   dest='usb', help='Show connected USB devices')
    p.add_argument('-u', "--usb", action='store_const', const=True, 
	               default=False, dest='usb', help='Show connected USB devices')
    p.add_argument("pattern", nargs='*', default='*', help="Name patterns")
    p = cmds.add_parser("version", help="show vws version")
    p = cmds.add_parser("autostart",
                        help="Autostart all VMs marked as autostartable")
    p = cmds.add_parser("shutdown", help="shut down all running VMs")
    p.add_argument('-w', "--wait", 
    p.add_argument("--wait", help="wait until all machines would be shoutdown",
                   help="wait until all machines would be shutdown",
                   action="store_const", const=True, default=False, dest="wait")
    p.add_argument("--timeout", type=int, default=90,
    p.add_argument('-t', "--timeout", type=int, default=90,
                   help="how long to way for VMs shutdown before forcing it off")
    # Power management
    p = new_command(cmds, 'start', help='Start VW and connect to console',
                    description="Start VW if not running and connect " +
                    "to the console")
    p.add_argument('--no-gui', dest='gui', action='store_const', const=False,
                   default=True, help='do not open console window')

    p.add_argument('snapname', help='snapshot name')
    p = new_command(cmds, 'revert', help='Revert to snapshot')
    p.add_argument('snapname', help='name of snapshot to revert to')
    p = new_command(cmds, 'commit',
                    help='Commit snapshot changes into backing file')
    p = new_command(cmds, 'snapshots', help='List existing snapshots')
    # Screenshoits and recording
    p = new_command(cmds, 'screenshot', help='take a screenshot')
    p.add_argument('filename', help='PPM image filename to write screenshot to')
    p = new_command(cmds, 'screenshot', help='take a screenshot',
                    description='Takes a screenshot',
                    epilog="""Writes current screen contents of the virtual machine into PPM format file""")
    p.add_argument('filename', metavar='filename.ppm',
	               help='PPM image filename to write screenshot to')
    p = new_command(cmds, 'record', help='Record audio output from VM')
    p.add_argument('filename', help='wav file to record autdio to')
    new_command(cmds, 'stoprecord', help='stop recording audio')
    p = new_command(cmds, 'sendkey', help='Send a keystroke to VM')
    p = new_command(cmds, 'sendkey', help='Send a keystroke to VM',
                    description='Send a key combination into VM',
                    epilog='Each key combination should be passed as separate' +
                    'argument.\nAll non-alphanumeric keys should be passed by' +
                    'names, not characters\n(see table in the manual).'
                    )
    p.add_argument('keyspec', help='key specification like ctrl-alt-delete',
                   nargs='+')
    # Create new VM
    p = new_command(cmds, 'create', help="Create new VW")
    p.add_argument("--no-usb", help="Disable USB controller", action='store_const',
                   const=False, default=True, dest="usb")
    p.add_argument("--size", metavar='size', help="Size of primary disk images",

**vws usb remove** *machine* [ *pattern* | **--address** *bus.device* ]

Detaches USB device.

SNAPSHOTS
---------

**vws snapshot** *machine*  *name*

Creates named snapshot. This means that there would be additional image
file for each virtual disks. All writes would go to new file, and
previous file would be unchanged until commit operation. Note that 
having long chain of snapshots significantly slower disk IO operations.

**vws** allows snapshots be made only when virtual machine is stopped.

**vws** **commit** *machine*

Writes changes in the current snapshot into previous one.
There would be one snapshot less for this machine after this operation.

If this operation is performed on stopped machine it operates on stack
of snapshots created by **vws** **snapshot** command.

If it is performed on running machine, this machine should run in the
snapshot mode (see **start** command for details) and changes made since
start in the snapshot mode are committed into permanent images.

**vws** **revert** *machine*

Discard changes made to disks since last **vms snapshot** command
and recreates snapshot. This command can be only performed
on stopped machine. Number of snapshots would be same after this
command.

**vws** **snapshots** *machine*

List named snapshots available for given machine. This command
can be used on running machine, despite of that machine must be shutdown 
before snapshots could be committed or reverted.

MISCELLANEA
-----------

**vws** allows to take virtual machine screenshot or record sound,
produced by virtual machine. One don't need to have GUI window open to
take screenshots.